An auxiliary power ram air turbine is typically deployed by a spring loaded actuator. Storing the ram air turbine means the compressed actuator may have a spring force of several thousand pounds ready to eject the ram air turbine when the release mechanism is actuated. Inadvertent release of such a device in the presence of ground crew could result in very serious injury. This could occur, for example, by the accidental release of the conventional locking mechanism for locking the ram air turbine in the stowed position.
U.S. Pat. No. 4,676,458 discloses one conventional deployment mechanism for a ram air turbine wherein a spring-loaded deployment actuator is operable to move the ram air turbine from a stowed position to a deployed position upon release of a conventional up-lock. U.S. Pat. No. 3,149,678 discloses wind motors for aircraft which are retractable into the body of the aircraft. A spring-loaded retraction jack moves the ram air turbine to the deployed position upon release of an up-lock.
U.S. Pat. No. 3,069,116 discloses emergency generator and vacuum producing means for airplanes wherein a combined generator and vacuum producing unit is projected to use position by a compressed, coiled spring upon the withdrawal of a manually released detent. None of these prior art devices provides a safety lock, in addition to the up-lock mechanism to prevent an inadvertent activation of the ram air turbine while the aircraft is being repaired or serviced.